This invention relates to vehicle headlamps in general and, in particular, to a sealing cap for vehicle headlamps and to a method of fabricating the sealing cap.
An aimable headlamp is known which comprises a lamp housing immovably mounted to a vehicle body, a reflector tiltably mounted to the lamp housing, and an electric bulb replaceably mounted to the reflector. The reflector together with the bulb is tilted relative to the reflector for aiming the beam of light thrown by the headlamp. The lamp housing has a relatively large access opening for electrical connection of the lamp bulb to a power supply and for replacement of the bulb. A disklike sealing cap is generally employed for watertightly closing the annular gap between the lamp housing edge defining the access opening and the base of the bulb.
One known sealing cap is a substantially disklike piece of rubber or like elastic material comprising a peripheral portion with an annular groove to engage a rim which is formed on the lamp housing so as to surround the access opening, a tubular central portion to fit over the base of a lamp bulb, and an annular, pleated intermediate portion joining the peripheral portion and the central portion.
An objection to this prior art device is that, in remounting the sealing cap as after bulb replacement, the groove in the peripheral portion may not properly engage the rim of the lamp housing. The peripheral portion must of necessity be of considerable thickness in order to prevent accidental detachment from the lamp housing. A touch on this thick peripheral portion was therefore insufficient to make sure that its groove was in full engagement with the lamp housing rim. Any incomplete engagement led to a failure in watertightly closing the gap between lamp housing and lamp bulb.
This weakness is absent from another known sealing cap which has an annular peripheral portion of L shaped cross section to engage the lamp housing rim. This second known sealing cap is intended for use with a separate disklike locking cap to fit over the sealing cap. The locking cap has an annular peripheral groove to engage the lamp housing rim together with the peripheral portion of the sealing cap and hence to lock the sealing cap in position on the lamp housing.
Once the locking cap is mounted in place, the sealing cap infallibly makes watertight engagement with the lamp housing. However, the necessity for manipulation of both sealing cap and locking cap made bulb replacement troublesome. Also, being engaged with the lamp housing via the elastic sealing cap, the locking cap required considerable manual effort for its mounting and dismounting. Although the locking cap had ribs formed on its periphery to prevent slipping, they were insufficient to afford a firm grip on the cap.
The two prior art devices discussed above are subject to an additional inconvenience in common. Both presuppose the existence of the annular rim on the lamp housing. This rim necessitated the use of sliding molds for the fabrication of the lamp housing. Such molds were complex and expensive in construction.